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Level Gauge and Transmitter for Buried Vessels

04/18/2012 2:50 AM

Dear All, please advise me if there is any other best option for a Level
Gauge other than Magnetic Type for a buried Vessel. And which would be the best
option to go with for a Level Transmitter for the same, either top mounted Magnetostrictive
Type or Guided Wave Radar Type. Magnetic Type seems to be difficult for
maintenance and trouble-shooting for me. Thank you all in advance.

Re: Level Gauge and Transmitter for Buried Vessels

04/18/2012 7:22 AM

The instrument would need to be an IP68-cased level transmitter suitable for the process fluids and temperature/pressure of operation, as a gauge could not be seen underground. It would need to be set-up and tested with the tank still exposed, probably filled with a test fluid such as water, which will need a lower temperature for the testing. That rules out capacitance as a measurement technique. The pressure is above ambient and if it and the temperature vary significantly, then ultrasonics will prove unreliable.

It's starting to look like magnetic follower or radar are measurement technique candidates, though it would be good if the housing containing the cable connections and any electronics could be separated from the tank thermally so it could operate at a lower temperature. If not, then some exotic transmission cable and gland types will be needed to withstand the temperatures; MICC cable will do it, as will pyro.

MICC and pyro do not lend themselves readily to hazardous area EEx i applications on the basis of energy storage without special considerations in circuit design. It would be better to go EEx de, if at all possible, if flammable gas/air mixtures are inside the tank, and use regular SWA cables with appropriate glanding.

Hopefully there are some pointers here.

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Re: Level Gauge and Transmitter for Buried Vessels

04/19/2012 9:56 AM

IF the tank is vented, could you use a very low volume bubbler, and measure the reflected back pressure to measure the liquid level? Air flow would be on the order of 2 to 5 cubic feet per hour, so no velocity impact to the back pressure in the piping. Transmitter could be located remotely in a safe enclosure.

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Re: Level Gauge and Transmitter for Buried Vessels

04/19/2012 11:52 AM

Further on what has already been asked, please send a detailed description of the product to be measured, like what it is, specific gravity or density, special considerations.

Also indicate if the tank is pressurized, if there are more than 1 product in the vessel, example like oil and water, if there is an interface measurement, the dimensions of the tank, other wise the answers besides being sarcastic will be useless.

Re: Level Gauge and Transmitter for Buried Vessels

The Siemens Sitrans LR250 radar level transmitter would most likely be ideal for this application. Here is a contact for the level measuring expert in India:

Mr. Sandeep Vaida, Siemens Sensors and Communication

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